Change transmission fluid or not?

There, you are wrong Ted. I disagree with John on whether or not there's "cause and effect" or just coincidence here, but John knows one HELL of a lot about Mopar automatics...

Reply to
Steve
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Dandy, but irrelevant.

Dandy, but irrelevant.

Indubitably.

Reply to
Daniel J. Stern

Given the nonsense he's spouting about clutch particles suspended in transmission fluid "improving friction characteristics", I would trust his "hell of a lot" of knowledge about as far as I can throw a big block A727.

Reply to
Daniel J. Stern

I don't think he said that at all. I think he agrees that the oil and filter should be changed regularly. He just thinks that if you don't do this for too long a period of time, and I don't know what he considers to be too long, then you shouldn't do it at all. I disagree with him, but in all fairness to him, I don't think he ever suggested what you state here.

Matt

Reply to
Matthew S. Whiting

What is your definition of HIGH MILEAGE? Is that different than high mileage? Is this 50,000 miles? 100,000 miles? 150,000 miles? What is the magic point at which changing the transmission fluid causes the transmission to magically stop functioning?

Matt

Reply to
Matthew S. Whiting

Also absolute rubbish as even the Greeks knew the world was spinning (well at least the educated ones did) and they also had a pretty close measurement of the diameter of the planet, and therefore were able to theorize that humans on the surface were travelling a lot faster than 40Mph.

Once again, more Star Trek science dredged up to try and prove a rediculous assumption.

Ted

Reply to
Ted Mittelstaedt

Sigh.

For his argument to have any internal consistency it logically follows that if you agree with it, you are agreeing that it's better to never change trans fluid. Let me explain.

I know that he isn't able to see this but you, as an engineer with a bit more experience in logic, should be able to understand this. You already are on the right track by pointing out that he's not defining high mileage.

If he is right and there's some point at which it's better to not change the fluid, then the only way this could be true is if it's a simple linear progresion.

The way John's argument works is that after a magical "high mileage point" is reached, I'll call it the break-even point, that it's better to not change the fluid. It follows then that the further (older) away the trans ages from this point that the better and better it is to not change the fluid. He already put forth this supposition by claiming the suspended friction material substitutes for missing friction material in the clutches, thus the less friction material in the cluches the more of it in suspension in the fluid and the more required to be in suspension in the fluid to make up for the missing material, etc. etc. I could repeat other arguments of his regarding varnish buildup that make the same point.

So far, like Star Treck science with regards to impossibilities like antimatter propulsion, this _seems_ right.

Where it becomes obvious that John's argument is silly is what happens BEFORE this break-even point.

Suppose the break point is 80,000 miles. So at 90,000 miles we are 10% better to not change the fluid, at 100,000 miles we are 20% better to not change the fluid, at 110,000 miles we are 30% better to not change the fluid, etc. John has not supplied a curve so we must make an assumption based on his argument, here.

Thus, then, at 70,000 miles we are only 10% better TO change the fluid, and at 60,000 miles we are 20% better TO change the fluid, at 50,000 miles we are 30% better TO change the fluid, etc.

All that is logical progression, and if you accept his argument for the post-break even point, you can't help but accept the inverse for pre-break even point. If you don't, I can easily use his arguments for post-break-even point to prove you must accept the pre-break point progression if you accept the post-break point.

But here is where his arguments break down, because he in effect wants to have his cake and eat it too.

That is, In Real Life if the trans has 10,000 miles on it it does not need a fluid change, because of the same wear factors John is citing for his post-break down reasoning. At 20,000 miles it only has a 10% need of fluid change. At 30,000 miles it only has a 20% need of fluid change, and so on.

And now you see why his arguments are impossible - because if you accept his premise that such a break even point even exists at all, you have to accept the reverse pre-break down progression I cited above (because it's the same argument) which of course collides with the wear factors going the other way from 0 miles onward, which also depend, once again, on the same premise he's citing for the existence of a break even point.

Thus, you now have a written logical proof that John's arguments are internally inconsistent, thus impossible. I know it's a bit tortuous to follow the written out logic, it would be a lot easier to graph the alleged wear curves. And there is also one other way to show his argument is inconsistent, which is a supposition way, which is done by supposing that the older and older the trans gets from new manufacture, the worse and worse it is to not change the fluid, until after break even point the process reverses and it gets better and better to not change the fluid, this is harder to write out but as simple to graph, and it also proves inconsistency.

The only solution is to accept that such "high mileage" transes that are worse off for fluid changes simply don't exist. And since nobody has demonstrated the existences of such transes in any kind of controlled lab, it's pretty obvious that John's supposition is a bunch of baloney.

Ted

Reply to
Ted Mittelstaedt

Steve, you can only carry "hands on" knowledge just so far.

John may know a lot about Mopar automatics from a practical standpoint, as he may have taken apart dozens or hundreds. But he is clearly lacking (perhaps he does not want to learn or perhaps he is too busy) any of the math or science behind why they work at all. As I said he does not sound like he owns a Chrysler 3 speed or 4 speed. He may own such, but he certainly does not sound like it.

If John wants to make up a theory of "why fluid changes destroy high mileage transmissions" then he needs to approach it like any real researcher. He needs to make a theory based on fluid chemistry, then build up some experiments to test this. For example, among other things he stated:

"The friction modifiers can cause the clutches to slip where they didn't before"

well it would be pretty easy don't you think to fabricate a test jig comprised of clutches, then pour old and new fluid over it while running tests, and observe the results. Then a spectrograph could be used to give a list of the additional materials in the old fluid, and whammo - you now have the formula for a clutch additive that stops slipping clutches in transmissions.

Then you go find a couple dozen vehicles with slipping transes and pour in your additive and wa-la - instant trans overhaul. John would end up with a magic fluid formula for extending high mileage transes which would put him in retirement on a yacht in the Carribean.

The fact, however, that no such fluid exists at the current time really ought to be more than ample proof that the idea that leaving ATF comtaminated with anything in a high mileage trans will help it is poppycock.

Ted

Reply to
Ted Mittelstaedt

Hi Folks,

I am the original poster and I have stayed out of this because I didn't think my $.02 was worth much here and I still don't.

I have just reread the whole thread. I have learned a lot but still don't know what conclusions to draw.

Some clarifications:

It is a four speed (1,2,3 & overdrive) with a 3.3 l engine with 150,000 miles. I have owned it for 100,000 miles. I assume it was properly serviced before I bought it. I had a "Speedo sensor" replaced 4,000 miles ago (speedometer went crazy, transmission started shifting strangely).

I don't think the transmission is "on its last legs." It works well nearly all the time. It hunts for fourth around 45. It has done that since I have had the vehicle with no apparent changes in behavior over time.

It has gotten stuck in second (is this called "safe mode"?) three times in the last 2,000 miles. Stopping and restarting has fixed the problem. It did it yesterday and I think I think it was triggered by not getting the shift lever quite far enough into Drive (Drive position is not a solid detent any more. If feels more as if the lever is leaning up against a stop on the right. A light up (counter clockwise) tap will pop it out of drive. I assume this is a linkage adjustment and have not fixed it because "ain't broke."

I am finding people passionately on both sides of the question. I don't know what to think.

Ted, you suggest a plan of research. I wonder if anyone has actually done this, possibly with other-than-Chrysler high mileage transmissions. Any suggestions on where to look?

This idea (that a high mileage, unserviced transmission should not have its fluid changed) does seem to have the characteristics of urban legend, but enough possibly valid points were raised that I don't know what conclusion to draw.

Joe Osborne Carlisle, PA

in article newscache$d8a8th$wvw$ snipped-for-privacy@news.ipinc.net, Ted Mittelstaedt at snipped-for-privacy@toybox.placo.com wrote on 2/17/04 7:19 AM:

Reply to
Joseph Osborne

Joseph,

Count the responses and I believe you'll find that the vast majority believe you should change the fluid and filter as this should only help the performance of the transmission. If you do this at the dealer, have them also make sure your computer has the latest programming as well and take a look at the shifter switch. I really doubt that any additional responses will give you the definitive answer you seek. (Personally, I would prefer to see this thread die a quick death, but expect your response will elicit a new flurry of posts.)

The bottom line here is it's your decision. But, please do post on what you decide and then follow up again in 6 months or so to let us know the consequences and how the transmission is performing.

Bob

Reply to
Bob Shuman

Got a little time on your hands Ted? Get a life.

Reply to
Rick Blaine

"Ted Mittelstaedt" a écrit dans le message de news:newscache$ux88th$zuw$ snipped-for-privacy@news.ipinc.net...

Hmmm...nice debate.

Consider this:

Got a 89 Buick Century Limited with a bit less than 300,000 km on the "tranny", looking at the tranny fluid, my mind tells me to change the fluid, it is brownish/redish like it have been burned, the car as been "inspected" by 5 (that's five) different mechanics ranging from the "little backyard independant" to the full fredged "dealer" passing by "Canadian Tire" and my brother (witch is a experienced mechanic) and they ALL (sorry for the caps) told me the same thing:

The tranny have more chances to fail if the fluid is changed. In clear: If it's not broken, dont fix it.

Draw your own conclusions, urban myth or voodoo science? For myself, I trust the opinion of 5 differents mecanics instead of what my feeling tells me.

Why 5 mecanics for such an old car you think? I didnt beleive them at first but after 5 identical opinions, I gave it up!

Reply to
Fastload

Yes, that is "limp mode" or "safe mode". Be advised, stopping and restarting has *NOT* fixed the problem, it has merely caused the transmission to go out of safe mode. By continuing to drive with an existing fault, you run the real risk of turning a minor, easily-corrected fault into a more major, more expensive repair.

There have been a great many updates to the firmware that runs your transmission control computer. It will benefit you to have your transmisison computer "flashed" (updated with the latest firmware) and your fluid and filter changed while the cause of your intermittent "safe mode" is determined and corrected.

DS

Reply to
Daniel J. Stern

Here's my opinion SPECIFIC to that transmission:

1) That transmission DEPENDS on good friction modifiers in the fluid to prevent harsh torque-convertor lockup, shudder, and torque-convertor clutch damage. The "hunting" you describe may actually be abrupt TC lock and release due to the friction modifiers being "worn out" in that fluid. 2) It is a demonstrated fact that ATF+3 friction modifiers DO deteriorate or "wear out" over time and miles. 3) If the TC clutch fails, it will plug everything else in sight and make it quite irrelevant how worn or not worn the rest of the transmission is. 4) That transmission gives you the ability to TELL how worn the clutches are by pulling information from the tranny controller with a scan tool. The logged clutch volumes change as the clutches wear, so you can get a good assessment of the state of the clutches without ever dropping the pan.

THEREFORE, I would recommend having a tranny shop pull the codes. If wear looks like its high, then start saving for a transmission repair and don't bother with the fluid change because odds are that the new fluid wouldn't be in there long enough to pay for itself. But if the clutch wear numbers look good, DO the fluid change and don't risk destroying the TC clutch (and the rest of the tranny) with worn-out fluid.

Reply to
Steve

All of what you say is true, but I see no more reason to "rip" on John than on me. I AM an engineer, but I haven't taken the time to run the tests you're talking about either.

To me its an interesting but largely academic point, and not really worth the effort to solve one way or the other. If I change the fluid in a tranny and it immediately quits working, my thought is "Thank GOD! That thing was about to strand me somewhere, I sure glad I found out in my garage instead" and not "Oh NO! It was working and now it isn't!" Because of that and because of the fact that the odds of it happening are low, I will never EVER under any circumstance advise against changing transmission fluid no matter how old or hard-ridden the transmission is.

Reply to
Steve

The vehicle in the original post has 150,000 miles, 100,000 of which are known to have had no transmission service and it is already exhibiting distress by occasionally going into the limp mode. (Read the original post) There is no guarantee that a fluid change under these conditions will cause the transmission to stop functioning but there is a possibility that it will, and that's all the original poster wanted to know. As stated earlier, many reputable transmission shops will to or recommend against fluid changes under these circumstances (let your fingers do the walking). John

Reply to
John Kunkel

Burned fluid IS "broken!"

Fix it. Does it increase the chance that the transmission will fail next week? Who cares, the odds are ALREADY in favor if it failing next week with burned fluid in it!

Reply to
Steve

Duh! Only an engineer would interpret vehicle speed by including the Earth's rotation. If I traveled east to get to my westerly neighbor's house, he lives 20,000 miles away. John

Reply to
John Kunkel

Irrelevant? Hardly.

Reply to
John Kunkel

On Tue, 17 Feb 2004, Steve wrote (to Ted, but I'm jumpin' in):

I see a very good reason: John's blithering-on about stuff that he obviously does not understand. He's using his imagination to come up with an explanation for what he thinks he's seen. It seems logical to him, and probably *is* logical if you start with his limited data and limited understanding. The problem is when he takes what he thinks he's seen and from it synthesizes what he thinks he knows, and then preaches that as if it's valid, when in fact what he's saying has zero scientific or engineering basis. I don't know why he's doing it -- perhaps because having the "answer" to a question makes him feel good -- but he is doing the original poster a great disservice by promulgating his guesses and opinions in terms of fact.

No, but you have a sufficiently thoroughgoing knowledge of transmission and lubricant science and engineering to comment meaningfully on the matter. I haven't seen any evidence that John can claim the same.

EXACTLY. Precisely. This is just what I mean: Even if we accept all of John's imaginative arguments about floating clutch crumbs improving frictional characteristics and whatnot, he's still wrong for just the reason you state: A transmission so far gone that it is pushed over the edge by a fluid and filter change was living on time borrowed at a usurious rate, and was imminently ready to fail. Much better for the failure to happen within sight of the shop than just sometime, just somewhere.

This is a sound, rational, well-thought-out position, and I'm not just saying that because I agree with it. John hasn't been able to provide anything but unsupportable assertions and insults, and for that reason alone he deserves more of a thumping in this thread than you do.

DS

Reply to
Daniel J. Stern

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